A force sensor based on FPI for flexible needle force sensing

In order to solve the problems of puncture force sensing error and delay during the puncturing of human tissue by flexible needle, a Fabry-Perot (FPI) sensor consisting of single-mode optical fibre and air cavity is proposed. The FPI was fixed to the tip of a flexible needle and puncture experiments were carried out on four different hardnesses of silicone. The experimental results show that the sensor not only has high resolution and sensitivity of the puncture force, which can effectively sense the small change of the cutting force during the puncture process, but also has a smaller time delay compared with the commercial force sensor, which can sense the change of the puncture force during the puncture process in time.